Regular maintenance of the bottom of the outboard motor is a critical condition for its long and trouble-free service. gearbox It's a transfer of torque from the engine shaft to the propeller, which is accompanied by tremendous mechanical stress and heating, and ignoring the need to replace the lubricant in this unit can lead to jamming of gears, destruction of bearings and, as a result, expensive overhaul of the entire unit.
Many boating owners mistakenly believe that the oil in the gearbox is poured once and for all or changes only when there are obvious signs of malfunction. This is a dangerous misconception, since over time the lubricating fluid loses its properties, and condensate or water can accumulate in the crankcase. oil replacement in the outboard motor gearbox This is not just a technical procedure, but a guarantee that your vacation on the water will not be overshadowed by a sudden breakage away from the shore.
In this article, we will take a closer look at the process of replacing lubricant, look at the nuances of material selection, and answer questions that often arise for beginners. You will learn why it is important to use the bottom hole for pouring and how to determine the condition of the osseous ossils from the appearance of the exhaust fluid. Attention to detail at this stage will save you significant funds in the future.
Preparation for the lubrication replacement procedure
Before any work with the bottom of the engine, you need to ensure a safe and convenient environment for the operation. The outboard motor must be securely fixed to the transom of the boat or installed on a special rack in a vertical position. The horizontal position of the engine is unacceptable, as this will lead to incorrect oil levels and possible air entering the lubrication system at start-up.
You'll need to prepare a minimum set of tools and materials to make the process go quickly and clean, the main tool will be a syringe for oil (manual or pneumatic), which allows you to apply the grease from the bottom up, displacing the air and residue of the old liquid, you will also need keys to unscrew the plugs, a drain tank, rags and, of course, a new oil that meets the specifications of your manufacturer. outboard.
It is important to let the engine cool completely before starting work if it has been recently used. Hot oil has less viscosity and can leak out too quickly, creating a messy situation, and there is a risk of burns. In addition, it is easier to notice the stains on the warm engine, but the replacement procedure is carried out on a cold or warm, but not hot unit.
⚠️ Attention: Before you unscrew the drain plug, make sure you can spin it back. If the thread is broken or the plug is lost, the engine will not be operated until the fault is corrected.
☑️ Preparation for oil replacement
Choosing the Right Oil for the Reductor
The quality and type of lubricant used directly affect the life of gears and bearings. gearbox Special oils are used that have increased corrosion-resistant properties and the ability to work in conditions of possible contact with water. Conventional car transmission fluids are not suitable here, as they can foam at high revs and do not have the necessary additives to protect non-ferrous metals.
When choosing a product, first of all, pay attention to the classification by API. Most modern motors require oil class. GL-5, which contains sulphur-phosphorus additives that protect hypoid transmissions from bullies, but some older models or low-power motors with bronze synchronizers may require a class of GL-4Therefore, consultation with the manual is mandatory.
The viscosity of the oil is chosen depending on the climatic conditions of operation and the manufacturer's recommendations. SAE 80W-90 or 85W-90In extremely low temperatures, more liquid synthetic compounds can be used to allow easy start and quick pumping.
Synthetics or mineral water?
Synthetic oils have better stability at temperature extremes and less foaming, but for motors with more mileage and worn-out ossils, mineral oil may be preferred because of its higher density and less propensity to leak through microgaps.
The table below will help you navigate the main parameters of oils for different conditions:
| Type of oil | Viscosity (SAE) | Class Class Class API | Recommended temperature conditions |
|---|---|---|---|
| Mineral | 80W-90 | GL-5 | Temperate climate, summer |
| Semi-intelligent | 75W-90 | GL-5 | All-season use |
| Synthetics | 75W-140 | GL-5 | High loads, hot climate |
| Specialized | 85W-90 | GL-4/GL-5 | Colored alloy motors |
Drainage of waste liquid and diagnosis
The process of removing the old oil is not only a hygienic procedure, but also an important step in diagnosing the condition of the node. First, locate the two plugs on the lower unit, the top and bottom, first unscrew the bottom stopper, and the oil begins to drain into the prepared container. Once the main flow weakens, the top stopper is unscrewed, which provides better fluid flow through air access.
The most important thing about draining is the visual analysis of the leaking substance, and if the oil is of normal color (from light brown to dark green) and has a uniform consistency, then it is a very simple matter. gearbox It's okay to have metal chips on the bottom plug magnet in the form of fine dust, but the large metal fragments indicate serious wear on the gears.
The most alarming signal is the appearance of an emulsion, a mixture of oil and water that looks like mayonnaise or coffee foam, which indicates that the body has depressurized and water enters the body, which may be caused by damaged glands, microcracks in the body or loosely twisted plugs, and the operation of the motor with water in the gearbox is strictly prohibited, as this will lead to corrosion and jamming.
If you find an emulsion, don't just change the oil. Rinse the gearbox with kerosene or diesel, dry and test the pressure tightness before refilling with new oil.
Technology of correct filling of the gearbox
The new oil has one critical feature: the liquid is fed exclusively through the bottom hole, and it's a physics-driven process, where the oil goes up from the bottom up, displaces air through the top hole, preventing the formation of air traffic jams. If you try to pour the oil on top, there will be voids in the body, which will lead to oil starvation of the gears at the first start.
Use a special syringe with a long nose that fits tightly into the thread of the bottom plug. Squeeze the oil slowly, watching the upper hole. As soon as the clean oil starts to flow out of the upper breath without air bubbles, the supply should be stopped immediately, at which point the gearbox is fully filled, and the necessary pressure is created in it.
The order of the corks is also important for creating the right vacuum when cooling, first quickly twisting the top cork to lock the volume of oil inside, then extracting the spout of the syringe and twisting the bottom cork, which ensures that when the oil cools down and the air compresses inside, there is no vacuum that could suck water through the coils.
⚠️ Attention: Never leave the gearbox open for long periods of time, and getting dust, sand or moisture inside the case is unacceptable and can destroy the rubbing fumes in minutes of operation.
Level control and leakage check
After filling, you need to carefully wipe the area of the plugs and check for no leakage. The level of oil is considered correct if it is located strictly along the upper edge of the lower hole (when the plug is twisted) or when there is no excess pressure when the plugs are twisted, pushing the lubricant outwards. In some designs, the level is controlled by the upper hole with the top plug twisted.
It's important to use new sealing washers under the plugs, and these little parts of lead, copper, or rubber cost a penny, but reuse often leads to leaks, and the old washer deforms when it first tightens and loses its sealing properties. Replacing washers with new ones at each procedure is a mandatory rule of professionals.
After assembly, it is advisable to test the engine on water or in a barrel, and then re-examine the area of lower unit. The thermal expansion of the oil and vibration can reveal weakly twisted plugs or defects in seals. If an hour after the engine is running under the boat there are no oil stains, the procedure can be considered successful.
The key is to use new sealing rings and pour oil strictly from the bottom up to eliminate air traffic jams.
Frequency of service and typical errors
The rule of changing the oil in the gearbox is usually spelled out in the instructions for use, and is usually 100 hours or once a year (before winter storage), ignoring seasonal replacement is dangerous because during the downtime in a cold garage, condensate trapped in the oil can cause corrosion of the internal surfaces.
One of the most common mistakes is oil overflows: excess fluid when heated creates excessive pressure that squeezes out the oels and leads to leaks; the other extreme is underwater, which causes overheating and wear; and there are also frequent cases of using inappropriate oils, such as motor oils, which foam in the gearbox and stop lubricating.
Remember that even if there are no obvious problems, regular replacement of lubricant prolongs the life of expensive parts. The cost of a liter of oil is not commensurate with the cost of a new pair of gears or the entire gearbox assembly. Treat maintenance of the bottom of the motor with due care, and it will respond with reliable traction.
What to do if a traffic jam is lost?
In emergency cases, you can use a temporary stub from the right material, but you can not operate the engine for a long time. It is better to have spare plugs and washers in the remplekt, since the carvings on the diewoods are standardized by brand (Yamaha, Mercury, Suzuki, etc.).
How often should you change the oil in the gearbox if the boat is rarely used?
Even if you only go out a few times a season, the oil needs to be changed at least once a year, preferably before the boat is put in winter storage, because during the downtime, condensation can form in the oil, which will lead to corrosion of parts.
Can I mix different oils from different manufacturers?
It is highly recommended not to mix oils of different brands or even different batches of the same manufacturer. The chemical composition of additives may differ, which will lead to the formation of sediment or loss of lubricating properties.
Why is the oil in the gearbox blackened?
Oil darkening is a natural process caused by heating and additives, but if the oil has become black and thick like tar, or has a burning smell, this may indicate overheating of the gearbox or wear of friction materials.
Do I need to wash the gearbox before pouring the new oil?
Washing is only required if an emulsion or metal shaving is found, if the oil has simply exhausted its life and is normal, drain it thoroughly enough and pour a new one in, and use of washing liquids is not necessary.
How much oil is required for the reducer?
Volume depends on the power and model of the motor. For small motors (2-5 hp), this is usually about 100-200 ml, for medium (15-30 hp) - 300-400 ml, and for powerful engines can reach 600-800 ml.